(a) The Field of The Invention
The present invention relates to a process for the preparation of Decabromodiphenyl ether having improved thermal stability.
Decabromodiphenyl ether, hereinafter referred to as "DECA" for the sake of brevity, is a well known flame retardant agent, useful in the preparation of articles made of polymeric material, to which it is desired to impart flame-retardant properties.
(b) The Prior Art
The art is crowded with processes for preparing DECA in a variety of solvents, ranging from liquid bromine to halogenated organic solvents. U.S. Pat. No. 4,521,633 discloses one of such processes in which DECA is prepared by reacting diphenyl ether in methylene chloride with a brominating agent in the presence of a catalyst, by initiating the reaction at a temperature of 15.degree. C. or lower, and then raising the temperature of the reaction mixture to an elevated temperature, typically the solvent reflux temperature.
U.S. Pat. No. 3,959,387 discloses a process for the preparation of polybrominated biphenyl oxides in which the reaction is carried out in methylene bromide as the solvent, at temperatures of from room temperature to 200.degree. C.